The invention relates to both, a method of incineration of solid and, if desired, liquid waste, and to an apparatus for carrying out the method. Such apparatus is disclosed in German Pat. No. 2654041. It comprises two vertically arranged superjacent chambers, i.e. a pyrolysis chamber and connected directly to its bottom outlet, a combustion chamber; exhaust gas ducts which cover the outer walls of the pyrolysis chamber either partly or completely in such a way that the covered wall surfaces of the pyrolysis chamber serve as the inner walls of the exhaust gas ducts; one or more swivelling gate elements between the pyrolysis and combustion chambers, the upper side of which elements is closed (i.e. is uninterrupted or unpierced; has no openings going through) while the swivelling gate elements are supported on a shaft or axle in such a way that, when moving them, passages of different cross-sections are obtained through which solid and gaseous products from the pyrolysis process are discharged from the pyrolysis chamber into the combustion chamber; and combustion air supply inlets which are arranged in flow direction behind the gate elements.
With the installation disclosed in German Pat. No. 2654041 wastes of different types can be incinerated without its presorting being necessary since, in dependence upon the combustion characteristics of the waste, the swivelling gate elements can discontinuously or continuously be operated, primary and secondary air can adequately be supplied, the waste and gas flows can efficiently be directed through the installation, and the necessary glow bed can properly develop in the pyrolysis chamber.
The gate elements serve to maintain the glow bed at the required depth and to permanently turn over its constituents. In dependence upon the cross-section of the passage between the gate elements, only particles of the desired small size are discharged into the lower combustion chamber. Besides regulating the waste and gas circulation within the installation by properly operating the swivelling gate elements, the recirculation of exhaust gas heat is of considerable importance for an economic pyrolysis and incineration process. Where the walls of the pyrolysis chamber are covered by the exhaust gas ducts, the waste heat of the exhaust gases is transferred through the walls to the waste flow and the center of the waste fill by heat conduction. Heat transfer is additionally favored by the slender design of the installation. With unchanging operation parameters, e.g. wall surface, exhaust gas temperature, the heat transfer through the walls of the pyrolysis chamber is unchanging too, and mainly depends on the geometrical shape of the pyrolysis chamber which means that independent regulation of either the drying, degassing or gasification processes in the individual sections of the pyrolysis chamber is aggravated.
It is an object of the present invention to affect the individual processes which take place in the prolysis chamber, independently from each other and to avoid their direct dependence upon the geometrical shape of the pyrolysis chamber.
Consequently, as a further development of the invention disclosed in German Pat. No. 2654041 the incineration installation of the present invention is characterized by the exhaust gas ducts on the outside walls of the pyrolysis chamber being vertically subdivided into individual partial ducts; these partial ducts being provided with gas outlets which penetrate the outside walls of the pyrolysis chamber where they are covered by the exhaust gas ducts, and enter into the pyrolysis chamber; whereby each individual part of the exhaust gas ducts serves to supply exhaust gas directly to the waste flow and to the center of the waste fill, in sections.
Via the gas outlets of the partial ducts leading into the pyrolysis chamber, partial flows of the exhaust gases are led directly into the pyrolysis chamber.
These partial flows are led separately from each other into the vertically arranged sections of the pyrolysis chamber in which the partial processes, i.e. drying, degassing, and gasification as well as partial combustion takes place. Thus, the heat and oxygen supply to these sections can be adjusted to actual requirements by simple regulating devices, and an interference or overlap of the partial processes is countered. According to the heat content of the exhaust gases, the temperatures of the exahust gas partial flows to the various partial ducts can individually be lowered by intermediate cooling and thus individually adjusted to the requirements of the partial processes within the pyrolysis chamber. It is also possible to adjust the oxygen content of each of the exhaust gas partial flows to the requirements of the partial processes within the pyrolysis chamber by air admixture. Heat supply is effected directly and thus quickly and efficiently right to the center of the waste fill since with the present invention heat transfer is carried out mainly by convection. In comparison with heat transfer by heat conduction, direct heat transfer offers the advantage of a more uniform temperature distribution over the chamber cross-section, due to a lower time constant. In addition, dependence of the temperature distribution upon the turnover of the waste fill is reduced. The heat and oxygen supply to each of the sections of the pyrolysis chamber is individually controllable by simple regulating devices arranged in the external piping system. The extent of these sections can be affected in the desired way, too.
In advantageous development of the main idea of the invention the combustion chamber which is connected at the outlet of the pyrolysis chamber, is subdivided into an incineration chamber for solid pyrolysis products and one for gaseous pyrolysis products. The latter one is paraxially connected to the solids incineration chamber. Both chambers are provided with secondary air supply openings in order to allow separate and independent regulation of the burn-out process of solid pyrolysis products and complete incineration of the gaseous ones. Only such an amount of combustion air is supplied to the solids incineration chamber as to just ensure the complete burn-out of the solid pyrolysis products passing through the opening which results from the movement of the swivelling gate elements, and the amount of combustion air supplied to the gas incineration chamber is regulated as to ensure complete incineration of the gaseous pyrolysis products. Thus, a low gas velocity is obtained in the solids incineration chamber and the deleterious effect of ash being carried along with the exhaust gases, is avoided. High gas velocities because of a larger amount of combustion air--the main part of secondary combustion air--supplied to the gaseous pyrolysis products as well as the expansion of exhaust gases when being burnt are encountered only in the gas incineration chamber.
Where movable and thus, delicate components of the installation are installed (especially in the transitional cross-section between pyrolysis chamber and solids incineration chamber), temperatures are low, whereas high temperatures develop only in the gas incineration chamber where the gaseous pyrolysis products are completely burnt, and which is separated from the other chambers of the installation.
There are some advantages when the bottom of the solids incineration chamber which is connected to the outlet of the pyrolysis chamber is also formed by one or more swivelling gate elements with a closed upper side and gas outlet openings on the under side from the movement of which result passages of different widths. With the air supplied through the gas outlet openings of these additional gate elements, the ash in the ash discharge chamber is cooled before the air is recirculated as combustion air through the passage of the second elements to the solid pyrolysis products resting on and being turned over by these gate elements.